1. Field of the Invention
The present invention relates to a reaction tank for causing agglutination reaction, for example, in immunological agglutination reaction.
2. Description of the Related Art
A reaction vessel (microplate) conventionally used in analysis and examination of a substance present in a specimen such as blood is formed as a plate-like vessel having plural reaction recesses called well formed and arranged in a matrix on one surface thereof. In each well of the microplate, a minute amount of specimen and reagent is dispensed to cause reaction in a reaction tank. An agglutinated substance produced by the reaction is subjected to measurement for the analysis of a substance present in the specimen.
Automatic analyzers have conventionally been proposed to automate the above-mentioned analysis. In the automatic analyzer, plural microplates are stored in a reaction line (reaction tank) until reaction time required for various types of analysis items elapses. Then, the microplate where the reaction finishes is sequentially taken out. Photometry is performed with a detector such as a CCD camera on each well, and an agglutination pattern is detected. Analysis of a substance present in the specimen is performed in such a manner (see Japanese Patent Application Laid-Open No. H5-273216, for example).
Generally, the reaction tank used in the conventional automatic analyzer as described above is configured with an evaporating dish arranged in a vessel storing the microplate. Water poured in the evaporating dish undergoes natural evaporation in the vessel to humidify an inside space of the vessel, and thereby causing agglutination reaction of the specimen in the well.
However, the humidity inside the vessel of the conventional reaction tank is difficult to control because the water in the evaporating dish is set to undergo natural evaporation. For example, if the water in the evaporating dish has not evaporated before the automatic analyzer starts analysis, humidity does not rise immediately and the start of the analysis can be delayed. In addition, when high-speed automatic analysis requires frequent transfer of the microplate in and out of the reaction tank, the humidity in the vessel of the reaction tank is difficult to maintain at a suitable level for the reaction.